Recently, demands on a small-sized compact camera module are on the increase for use in various multimedia fields including notebook type personal computers, camera phones, PDAs (Personal Digital Assistants), smart phones and toys, and further in image input equipment including monitoring cameras and information terminals for video tape recorders. Particularly, designs are elements that have a great influence on sales of mobile phones, whereby small-sized camera modules are greatly demanded.
The camera module generally includes a holder, a PCB (Printed Circuit Board), an optical system, a filter and an image sensor. The holder is formed with an insertion hole for inserting lenses, and is mounted thereunder with the PCB. The PCB is mounted thereon with an image sensor or a photoelectric conversion device such as a CCD (Charge Coupled Apparatus) type or a CMOS (Complementary Metal Oxide Semiconductor) type to converge light from an object to a photosensitive element and to form an image of the object.
FIG. 1 is a perspective view illustrating a holder structure of a camera module according to prior art, and FIG. 2 is a perspective view illustrating a rear structure of the holder structure.
Referring to FIG. 1, an exterior of a housing (1) is closed, and the housing (1) is formed with an upper surface-opened lens insertion hole (2) into which a lens can be inserted.
Referring to FIG. 2, a rear surface of the housing (1) is formed with a filter attachment (3) for attaching an infrared blocking filter, and one side of the rear surface is formed with an outlet (4) for discharging fumes generated in the course of process.
As illustrated by dotted lines in FIG. 2, an adhesive is coated on three surfaces of the filter attachment (3) to prevent the outlet (4) from being blocked. The coating of adhesive only on three surfaces decreases an attachment force of the filter, and may cause defects such as burning and degradation due to residual fumes remaining in the narrowed fume-discharging outlet.
Another disadvantage in the conventional camera module is that a high temperature heat is not discharged outside after a process of bonding a holder and a PCB under the high temperature of more than 80 Celsius, resulting in generation of deformed parts, defects, decrease in resolution, burning and/or degradation caused by deformed plastic lens.
Particularly, a reflowable camera module through an SMD (Surface Mount Device) process undergoes a very high temperature of more than 260 Celsius, such that a radiating measure is very important, in addition to measures to prevent generation of defects in the manufacturing course.
A plastic material having a high thermal conductivity has been conventionally used to solve the aforementioned disadvantages, or radiating methods including a double injection molding of a metal and use of coated surface layer have been utilized. However, these methods have disadvantageously increased costs in parts and processing procedures. Furthermore, these methods are weak to control on foreign objects.